Hydraulic pumps



Dec. 17, 1963 J. ROLLITT 3,114,328

' HYDRAULIC PUMPS Filed Dec. 20, 1960 a Sheets-Sheet 2 INVENTOR:

JOHN ROLLITT.

United States Patent 3,114,328 J h I HYDRAULIC PUMPS 0 n Rollrtt, Copmanthorpe, York, England, assignor to Armstrong Patents Co. Limited, London, England Filed Dec. 20, E950, Ser. No. 77,173 Claims priority, application Great Britain June 24-, 1969 2 Claims. (Cl. 193-473) Tms invention concerns hydraulic pumps, and relates more particularly to such pumps for use as sources of hydraulic medium under pressure, for example in hydrau- 110 remote control systems.

It is an object of the invention to provide a hydraulic pump unit which is particularly suitable for driving by means of an electric motor or other prime mover.

According to the present invention, a hydraulic pump unit comprises a housing, a shaft journalled within said housing and adapted for rotation from externally thereof, an eccentric fixedly mounted on said shaft within said hous ng, non-rotatable follower means coupled to said eccentric and reciprocable responsive to rotation of said eccentric by said shaft, and plunger operated hydraulic pump means within said housing and having the plunger thereof reciprocable by said follower means for transferring hydraulic medium from a source thereof to an outlet in said housing.

Preferably the housing is at least partly hollow, when the hollow interior of said housing may conveniently constitute a reservoir for hydraulic medium, the pump means then communicating directly with said reservoir. A preferred eccentric follower means is in the form of a banjo bush embracing the eccentric and having a generally radially directed neck presenting a fastening for one end of a connecting rod, the other end of which is slidably engaged in a guide secured to the housing. Conveniently, the housing is generally in the form of a right rectangular prism, with the shaft journalled transversely therein substantially centrally between the two ends of the housing, the pump means arranged between said shaft and one of said ends, and the connecting rod and its guide arranged between the other side of the shaft and the opposite said end. Where the pumping unit proposed by the invention is intended for supplying hydraulic medium under pressure through twin conduits to double-acting hydraulic apparatus capable of adopting one or other of two end con ditions, the said pumping unit may be provided with control means for directing the hydraulic medium selectively to said conduits.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a vertical section, taken on the line 1-1 of FIG. 2, through a pumping unit embodying the invention;

FIG. 2 is a section taken on the line 11-11 of FIG. 1,

FIG. 3 is a section taken on the line IIIHI of FIG. 1, and

FIG. 4 is a sectional detail, to an enlarged scale, of a hydraulic locking valve.

In the unit shown in the drawings, a generally hollow housing 1d has its hollow interior divided by a transverse partition ltla into a hydraulic medium reservoir portion 11 and an adjoining and communicating pump chamber portion 15. The housing ill has a hollow shaft 12 journalled therein in the pump chamber 13, and the shaft 12 is adapted for driving from externally by means of an electric motor 14, the output shaft 16 of which is shown as being engaged witlun and keyed to the shaft 12. It will, of course, be appreciated that the shaft 12 may alternatively be driven by any other prime mover, if desired, or may be provided with a pulley for receiving a driving belt.

Below the shaft 12, within an upstanding boss 18, is contained a capsule in the form of a cylinder 29 having a piston or pumping plunger 22 slidable therein. The pumpingplunger 22 is axially bored to provide a flow "sage 2 1 for hydraulic medium through said plunger, d said passage 24 is counterbored to receive a valve seat against which is resiliently urged an inlet valve ball 3 The end of the capsule 29 remote from the shaft 2 is provided with a closure member 3% having a valve seat 32 therein, and an outlet valve ball 34 is resiliently urged against the seat 32.

The shaft 12 carries an eccentric 36 fixedly mounted thereon, and this eccentric is in turn embraced by a banjo bush 33 constituting a follower, a sleeve bearing 40 being interposed betwee the eccentric 36 and bush 38. Formed in partition ltla is an opening l-ilb. The generally radially extending neck 39 of the bush 38 is recessed to receive one end of a connecting rod 42. As is illustrated in FIGS. 1 and 2, guide member 4-4 has received therein a cylindrical sleeve or bush 43 which is retained in guide member dd by an aperture cap 45. The free end of connecting rod 42 is loosely guided within the sleeve 43 with a clearance provided between the internal diameter of sleeve 43 and the aperture of cap 45, and connecting rod 52. Sleeve i3 is of a material having low friction properties so that as the eccentric 36 rotates, rod 42 loosely reciprocates in sleeve 43. The clearance between rod 2 and sleeve 43 permits a sufiicient amount of play to allow rod 42 to reciprocate in sleeve 43 upon rotation of eccentric 38.

In the operation of the pumping unit described, the pump means comprising the capsule Z0, plunger 22 and associated inlet and outlet valves delivers hydraulic medium from the pump chamber 13 to one or other of two outlets 5b which are provided in a control unit 46. The said pump means delivers the hydraulic medium from the lower end of the capsule 2-9 to the interior 19 of the boss 18, and thence to an inlet passage 43 of the control unit 4%, and the control unit 46, by selective positioning of a piston 52 in a bore 54 communicating with the inlet passage 48, enables the delivered hydraulic medium to be directed to the desired one of the two outlets 50.

For this purpose, as shown in FIG. 3, the bore 54 is formed with diametrically enlarged regions 64, 66 and 68, and the piston 5'32 has its external surface recessed at 7% and 72 to co-operate with the enlarged regions of the bore. One end of the piston 52. projects from the bore 54, and is formed with a transverse slot 74 wherein is freely engaged a peg (not shown) upstanding from a selector handle 56 which is pivoted at '76 to the body 19. The enlarged diameter region 66 of the bore 54 communicates by way of the passage with the delivery chamber 19 of the pump, and thus, depending on the setting of the handle 56 and therefore of the piston 52, hydraulic medium delivered to the region 66 passes along the recess 'lti to either the enlarged region 64 or the enlarged region 68 of the bore 54. From these latter regions, passages '73, hit lead to a further bore 82, at opposite end regions of which the outlets 5d are arranged, the region of the bore 82 between the passages '73, bllbeing occupied by a floating piston 84 fitted at each end with a restoring spring 86. Thus, depending upon the aforementioned setting of the selector handle 55, hydraulic medium is delivered to one or other of the outlets 50.

The hydraulic medium iiow path from the bore 82 to each outlet Slit however also includes a hydraulic locking valve for ensuring that, when the pump is used to supply a double-acting hydraulic apparatus, a load displaced in one direction by that apparatus is maintained in its displaced position until the direction of flow of the hydraulic medium is deliberately reversed by moving the handle 56. One of the locking valves is shown in detail in FIG. 4, and will be seen to include a valve ball 88 resiliently urged by means of a spring 90 on to a seat 92. The valve a ball 83, spring 90 and seat 92 are retained within a hollow plug member 94, sealing the end of the bore 32, by means of a retaining nut 96 which is axially bored at 93 and counterbored at 1% to receive a push rod N2 having a radial annular flange 104 between its ends. The plug member 94 is formed with radial bores 1G6 opening into an annular recess 1th, to allow the passage of hydraulic medium past the valve ball 83 into the outlet 50. As soon as the pumping unit is stopped, however, and the pressure of hydraulic medium acting to hold the valve ball 88 off its seat falls, the valve ball will close on to the seat 92 under the action or" the return spring 90, and this action is in turn reinforced by the reaction of the displaced load which is transmitted to the ball 88 through the hydraulic medium behind it, with the result that the displaced load is, in effect, locked in its displaced position.

Since provision must be made, in operating a doubleacting hydraulic apparatus, for the return of hydraulic medium from one part of the apparatus at the same time as hydraulic medium under pressure is being supplied from the pumping unit to another part of the apparatus, it will be noted that when pressurized hydraulic medium is directed through the bore 82 to one of the outlets St the heating piston 84 is displaced by that hydraulic medium towards the other end of the bore 52. This causes the piston 34 to bear against the push rod 182 and that end of said bore, thereby unseating the associated valve ball 88 to enable returning hydraulic medium to enter the bore 82 through the other outlet 50. From the bore 82, the returning hydraulic medium passes through the appropriate one of the passages 78, 8t) and then either directly into the end of the bore 54 adjacent the enlarged diameter region 6 or indirectly into said end, by way of the enlarged diameter region 68 and an axial bore 53 of the piston 52. Adjacent the enlarged diameter region 64, a generally radial passage 61 opens at one end into the bore 54, and at the other end registers with an inlet 60 to the housing 10, from which the returning hydraulic medium flows through a filter tube 62 back into the reservoir 11. It will be appreciated that the particular pump and control unit construction shown by way of example in the drawings is intended to cooperate with a double-acting hydraulic apparatus to which hydraulic medium is fed by two separate pipe lines respectively connected to the outlets i and that appropriate positioning of the selector handle 56 will accordingly determine which of its two possible end conditions is sought by the hydraulic apparatus. However, where the pumping unit proposed by the invention is required simply to deliver a single supply of hydraulic medium under pressure, it will be clear that the control unit 46 may be omitted. Similarly, the hydraulic locking valves may be omitted from the control unit if desired, leaving the unit 4-6 operating simply as a changeover device to select a required one of the two outlets St) to receive the pump delivery.

The operation of the pumping unit will be clear from the foregoing description, in that rotation of shaft 12 and hence of the eccentric 36 results in reciprocation of the bush 38, which at the same time is restrained from rotation by the connecting rod 42. The plunger 22, which is resiliently urged against the bush 38, is thus reciprocated to supply hydraulic medium under pressure to the control unit 46 and thence to the selected outlet 50. To provide a by-pass for the situation in which the hydraulic apparatus which is supplied with the pressurized hydraulic medium has reached its selected end condition, there is a spring-loaded relief valve 58 mounted in the housing 10 communicating with the interior 19 of the boss 18. The relief valve 58 is set to open when a predetermined maximum pressure occurs in the interior of the boss 18, and bypasses hydraulic medium from that interior back into the reservoir 11.

I claim:

1. A hydraulic pump unit comprising a housing, means definins a pump chamber and a reservoir chamber in the interior of the housing, a partition separating the reservoir chamber from the pump chamber and defining one end of each chamber, an opening in the partition providing communication between the reservoir and pump chambers, at least one hydraulic medium outlet in the opposite end of the pump chamber from the partition, a rotatable shaft journalled transversely across the pump chamber portion of said housing, an eccentric fixedly mounted on said shaft within the pump chamber, a fixed guide member in the reservoir chamber, a banjo bush embracing said eccentric, reciprocating pump means in the pump chamber communicating with said outlet with the operating plunger thereof engaging said banjo bush, and a connecting rod extending through said opening with one end secured to said banjo bush and its other end loosely and slidably received in said guide member whereby said bush is reciprocable responsive to rotation of said shaft.

2. A pump unit as set forth in claim 1 wherein said pump means comprise an axially bored cylinder having one end engaged in said housing over said outlet, said cylinder extending towards said shaft, a through-bored piston slidably received in said cylinder and having an inlet valve arranged therein, spring means in said cylinder for resiliently urging the free end of said piston against said bush, and a closure member including a delivery valve at the said end of said cylinder, said delivery valve being arranged to pass hydraulic medium to said outlet.

References (Iited in the file of this patent UNITED STATES PATENTS 1,286,958 Dinesen Dec. 10, 1918 1,771,607 Beebe July 29, 1930 2,040,667 Moulet May 12, 1936 2,288,963 Von Tavel July 7, 1942 3,021,716 Goyette et al Feb. 20, 1962 

1. A HYDRAULIC PUMP UNIT COMPRISING A HOUSING, MEANS DEFINING A PUMP CHAMBER AND A RESERVOIR CHAMBER IN THE INTERIOR OF THE HOUSING, A PARTITION SEPARATING THE RESERVOIR CHAMBER FROM THE PUMP CHAMBER AND DEFINING ONE END OF EACH CHAMBER, AN OPENING IN THE PARTITION PROVIDING COMMUNICATION BETWEEN THE RESERVOIR AND PUMP CHAMBERS, AT LEAST ONE HYDRAULIC MEDIUM OUTLET IN THE OPPOSITE END OF THE PUMP CHAMBER FROM THE PARTITION, A ROTATABLE SHAFT JOURNALLED TRANSVERSELY ACROSS THE PUMP CHAMBER PORTION OF SAID HOUSING, AN ECCENTRIC FIXEDLY MOUNTED ON SAID SHAFT WITHIN THE PUMP CHAMBER, A FIXED GUIDE MEMBER IN THE RESERVOIR CHAMBER, A BANJO BUSH EMBRACING SAID ECCENTRIC, RECIPROCATING PUMP MEANS IN THE PUMP CHAMBER COMMUNICATING WITH SAID OUTLET WITH THE OPERATING PLUNGER THEREOF ENGAGING SAID BANJO BUSH, AND A CONNECTING ROD EXTENDING THROUGH SAID OPENING WITH ONE END SECURED TO SAID BANJO BUSH AND ITS OTHER END LOOSELY AND SLIDABLY RECEIVED IN SAID GUIDE MEMBER WHEREBY SAID BUSH IS RECIPROCABLE RESPONSIVE TO ROTATION OF SAID SHAFT. 